Emerging contaminants are chemical products that are found in low concentrations, are not regulated by environmental norms, and cause health effects. Among this group of contaminants are parabens, a family of p-hydroxybenzoic acid esters used as preservatives in cosmetics, pharmaceuticals, and food products. Recent research describes parabens as endocrine disruptors that can cause health alterations. Some of the best alternatives for pollutant removal include the adsorption process, which can use materials that are inexpensive, abundant, and susceptible to modifications. In this sense, cellulose can be an option for obtaining materials that can be used in the removal of contaminants. This research investigates the synthesis of benzoic cellulose (MCB) and magnetic cellulose (MCM) as well as its use as an adsorbent for the removal of methylparaben (MP) and butylparaben (BP) from water. Likewise, physicochemical characterization, including Fourier transform infrared (FTIR), scanning electronic microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), and thermogravimetric analysis (TGA), for both cellulose materials was carried out. Moreover, pseudo-first-order, pseudo-second-order, Elovich, Weber, Morris, and Boyd models were used to investigate the adsorption kinetics. As a result, the pseudo-second-order model was favorable for both modified cellulose and the two parabens assayed. Finally, Freundlich, Langmuir, and Sips adsorption isotherm models were investigated; the Langmuir model was the best for the adsorption isotherm data. The adsorption of methylparaben and butylparaben was in the following order: MCM > MCB. The maximum adsorption capacity of MP and BP for MCM was 9.58 and 12.03 mg g–1, respectively. For instance, the results showed that the modified cellulose adsorbed the parabens physically, which could involve electrostatic attraction, hydrogen bonding, π–π bonding, and hydrophobic interactions.

The oxidation of aqueous solutions containing Allura Red AC (AR–AC) using bicarbonate-activated peroxide (BAP) and cobalt-impregnated pillared clay (Co/Al–PILC) as the catalyst was investigated. Using the CCD-RMS approach (central composite design–response surface methodology), the effects of dye, H₂O₂, and NaHCO₃ concentrations on AR–AC degradation were studied. The decolorization, total nitrogen (TN), and total carbon (TC) removals were the analyzed responses, and the experimental data were fitted to empirical quadratic equations for these responses, obtaining coefficients of determination R² and adjusted-R² higher than 0.9528. The multi-objective optimization conditions were [dye] = 21.25 mg/L, [H₂O₂] = 2.59 mM, [NaHCO₃] = 1.25 mM, and a catalyst loading of 2 g/L. Under these conditions, a decolorization greater than 99.43% was obtained, as well as TN and TC removals of 72.82 and 18.74%, respectively, with the added advantage of showing cobalt leaching below 0.01 mg/L. Chromatographic analyses (GC–MS and HPLC) were used to identify some reaction intermediates and by-products. This research showed that wastewater containing azo dyes may be treated using the cobalt-catalyzed BAP system in heterogeneous media.

El objetivo de este trabajo fue desarrollar un método por cromatografía iónica con detector de conductividad para la determinación simultánea de tiocianato en aguas residuales mineras y aniones como bromuro, cloruro, fluoruro, fosfato, nitrito, nitrato y sulfato. Como eluente se utilizó hidróxido de potasio (KOH) en un rango de concentraciones entre , flujos entre y corriente del supresor entre . Se determinó que la mejor separación de las especies estudiadas se logró con una concentración de KOH de en modo isocrático y un flujo de en una columna analítica AS20. Además, se determinó una serie de parámetros analíticos como sensibilidad, linealidad, precisión, exactitud y límites de detección y cuantificación que permiten la validación del método analítico. Se obtuvieron valores de desviación estándar relativa (RSD) menores al 20 % en cuanto a la precisión del método analítico, con recuperaciones mayores al 96 %. El método desarrollado es por lo tanto adecuado para la determinación de tiocianato y aniones en aguas residuales de origen minero. The objective of this work was to develop a method by ion chromatography with conductivity detector for the simultaneous determination of thiocyanate in mining wastewater and anions such as bromide, chloride, fluoride, phosphate, nitrite, nitrate and sulfate. Potassium hydroxide (KOH) was used as an eluent in a range of concentrations between , flows between and suppressor current between . It was determined that the best separation of the species was achieved with a KOH concentration of in isocratic mode and a flow of in an AS20 analytical column. In addition, a series of analytical parameters such as sensitivity, linearity, precision, accuracy and limits of detection and quantification were determined that allow the validation of the analytical method. Relative standard deviation (RSD) values of less than 20 % were obtained in terms of the accuracy of the analytical method, with recoveries greater than 96 %. The method developed is therefore suitable for the determination of thiocyanate and anions in wastewater of mining origin.

Se investiga la oxidación de fenol sobre catalizador de arcilla pilarizada en un reactor operando tanto en batch como en semibatch. Los experimentos fueron llevados a cabo a temperatura ambiente y presión atmosférica, con concentración de fenol de 100 mg/L, concentración de catalizador de 0,5 y 2,75 g/L y concentración de peróxido de hidrógeno del 50 y el 100 % de la cantidad estequiométrica necesaria para la total degradación de fenol. Se comparan ambos procesos en términos de degradación de fenol, degradación de H2O2, formación y degradación de intermediarios aromáticos y ácidos de cadena corta. Se determinó, que la velocidad de degradación de fenol e intermediarios aromáticos es más lenta en el proceso en semibatch. Sin embargo, hay un uso más eficiente del peróxido de hidrógeno en el proceso semibatch, favoreciendo la reacción con las especies orgánicas y reduciendo las reacciones competitivas.

The discharge of metal-complex dyes from textile industries poses significant environmental challenges due to their chemical stability and resistance to conventional biological treatment. This study examined the degradation of Acid Black 194 (AB–194), a 1:2 chromium-complex azo dye, using Co²⁺-activated peroxymonosulfate (PMS). A central composite design based on response surface methodology was used to evaluate the effects of Co²⁺ (5.93–20.07 µM), PMS (1.67–7.33 mM), and dye (13.79–56.21 mg L⁻¹) concentrations on decolorization and mineralization. The polynomial models demonstrated strong predictive accuracy (R² > 0.9896), identifying Co²⁺ and dye concentrations as the most influential factors. Under optimal conditions (18.0 µM Co²⁺, 6.5 mM PMS, 20.0 mg L⁻¹ dye), 99.19% decolorization was achieved at 30 min and 41.43% TOC removal at 240 min. Degradation kinetics were described by a mechanistic model incorporating 15 elementary reactions that comprise the Co²⁺/Co³⁺ redox cycle, radical generation, and dye oxidation, yielding a global R² of 0.9617. Estimated rate constants for dye oxidation (k₁₄ = 3.52 × 10⁹ M^–1 s^–1 for and k₁₅ = 2.00 × 10¹⁰ M^–1 s^–1 ) were consistent with values reported for aromatic compounds in sulfate radical systems. Radical contribution analysis confirmed sulfate radicals as the principal oxidizing species, accounting for 96.75% of the overall process.